(a) Field of the Invention
The present invention relates to a method of manufacturing a magnetic recording medium and, more specifically, to a method of manufacturing a magnetic recording medium which is optimally employable for the improvement of the corrosion resistance of a magnetic recording medium made of a ferromagnetic metal layer.
(b) Prior Art Statement
For improving the recording density of conventional magnetic recording media, great efforts have been made to improve the properties of the media themselves and to reduce the thickness thereof. Similarly for the improved recording density of the magnetic recording media, it has been proposed to reduce the spacing between the magnetic recording medium and recording/reproduction head. Among others, a magnetic recording medium is known which uses a ferromagnetic metal layer formed by sputtering and evaporation and which has excellent properties and reduced thickness. For maintaining the performance as a recording medium, however, these magnetic recording media need a protective layer, lubricating layer or both to improve the corrosion resistance and sliding resistance.
The aforementioned magnetic recording media having protective and lubricating layers for improved reliability are disclosed in, for exapple, Japanese Unexamined Patent Publication Nos. 57-18028, 56-114131 and 57-138054.
As described in the foregoing, the conventional magnetic recording media require a protective layer to improve the corrosion resistance of the ferromagnetic metal layer; in the conventional techniques of manufacturing the magneiic recording media, however, no consideration has been given to the adhesion between the ferromagnetic metal layer and protective layer and the consistency of the manufacturing process. More particularly, since the protective layer is generally formed with quite a different material from that of the ferromagnetic metal layer, the adhesion between them is insufficient so that the protective layer is apt to be separated as the case may be. Thus, the ferromagnetic metal layer is corroded so that the performance of the magnetic recording medium cannot be maintained and also its reliability is low.
Furthermore, since the ferromagnetic metal layer and protective layer are formed in different processes, respectively, no consistency can be ensured between the forming process and equipment. Thus, the forming process and equipment are complicated, resulting in a reduced manufacturing efficiency.